1. Field of the Invention
The present invention relates generally to a method and apparatus for cyclic compression of a body""s extremities, as well as a related system with a housing for containing and mounting the device on the foot board of a hospital bed.
2. Related Art
Medical devices that apply cyclic pressure to a person""s legs, arms, hands and/or feet are very old and well-known in the art. Many have employed pulsating pads, pistons and plungers for improving circulation. Others have used hydraulic and pneumatic bladders for similar purposes. The shapes, sizes, and composition of such bladders, pads and the like are widely varied, depending largely on their particular application.
Man has known the fundamental principle of most cyclic compression devices for many years. They are merely a more recent embodiment of the old art of massage, which has probably been used to stimulate circulation for ages. Use of mechanical devices to effect the massaging action is obviously more recent, but has a clear history of over a century.
Full understanding of the mechanism involved in this form of improving blood flow is more recent but has not fundamentally changed the devices used to accomplish this result. Veins have long been known to contain a series of one-way check valves along their length. Thus, when pressure is applied, compressing a vein, the fluid expelled therefrom can only proceed in the direction of normal circulation. When such compression is relaxed, the vein returns to its normal circular cross-section and the flow of blood into the vein is increased until it reaches its normal state of back pressure. Repeating this cycle in a cyclic fashion thus increases blood flow in the normal direction of circulation.
Such compression decompression cycles occur naturally in humans as part of the action of the muscles and flexure of the limbs. It has been known for many decades that the foot includes a large venous plexus (or group of veins). It is also known that this venous plexus is compressed during normal walking or running, thereby stimulating circulation. This efficient circulation aid is a marvelous design by our Creator, as its effect is greatest when the leg muscles (the largest muscles in the body) are in action and need the oxygen supplied by enhanced circulation.
For these and other reasons, the foot has long been known as an effective site for applying cyclic pressure. For instance, many devices such as Massator""s xe2x80x9cPediPulsorxe2x80x9d improve circulation by positioning a pulsating, dome-shaped pad in the arch of the foot. Many others have targeted the arch of the foot with flexible pneumatic chambers. A partial sampling of such pneumatic devices that target the arch of the foot are described in the masters thesis of James C. W. Parrott, B. Sc., B. Sc. (Med.), M.D., entitled The Effect Of A Mechanical Venous Pump On The Circulation In The Feet In The Presence Of Arterial Obstruction, and dated October, 1992 and found in the University of Manitoba library and includes Japanese Utility Model No. 72-10392, U.S. Pat. No. 4,614,180 in the name of Gardner and Fox, and U.S. Pat. No. 4,941,458 in the name of Taheri.
Many others have long recognized that the foot contains veins that can be massaged or pumped to provide better circulation. Some examples are: U.S. Pat. Nos. 3,824,992 and 3,901,221 to Nicholson, et al; Richard Dillon M.D. whose Journal of Vascular Diseases, January 1986 report on treatment of circulation-impaired patients states xe2x80x9ccompression boot therapy enjoys a 173 year history;xe2x80x9d and P. Gaskell M.D. and J. C. W. Parrott M.D. whose Surgery, Gynecology, and Obstetrics, April 1978 report, which is a summary of Dr. Parrott""s Master""s Thesis, documented an early demonstration of the process of venous pumping with pulsed air by stating xe2x80x9cWe have found that the boot covering the foot alone is simpler, less cumbersome, and gives a greater reduction of venous pressure than either a large cuff which covers the whole calf or a boot which includes the calf and the foot.xe2x80x9d
Such devices and many other medical devices are typically auxiliary devices which may or may not be employed on each patient. Because of their auxiliary nature, it is beneficial for such devices to be compact, portable and easily employed and stored adjacent a hospital bed. Other devices have addressed such concerns with hooks that allow the device to be hung on the foot board of a bed. However, because of the wide range of foot board sizes that must be accommodated, such hooks either have to be customized for certain foot boards, or else the snugness and security of the fit must be compromised. Further background and many other related references are known to those of skill in this art.
Despite the long history of technological developments of such housings and compression devices, man continues in his manifest pursuit of the ideal system which balances maximum therapeutic benefit with practicality and patient comfort.
Many other problems, obstacles and deficiencies faced in these fields and/or addressed by the present invention will be apparent to those skilled in that art, especially in light of the further descriptions herein.
It is a primary object of the present invention to provide a new and improved cyclic compression system which overcomes the problems and deficiencies of the prior art.
It is also an object of the present invention to provide a novel housing which can be conveniently handled and simply but securely mounted to a hospital bed or the like. Another object of the invention is to produce a simple, compact, inexpensive pump and housing which are capable of yielding substantial therapeutic and prophylactic benefits despite their small size and simplicity.
The present invention is directed toward accomplishing such objects and others and improving upon the teachings of the prior art by uniquely combining, refining and modifying various concepts and features to provide a significant advancement in the field. A primary object of the invention is to provide a small, lightweight and comfortable but durable device which helps prevent and/or solve many of the problems associated with impaired or poor circulation.
Another object includes providing a pneumatic device of simple construction which encloses as much of the foot as possible in order to squeeze as much of the foot as possible. Particularly it is an object to enclose those portions which may be readily compressed to improve circulation while allowing other less compressible portions to be open to the air. Still other objects include providing comfort and moisture control and avoiding the need for accessories such as additional stockings, wraps, sandals, straps, and the like, which have been required by the prior art.
Another object of the present invention is to provide an intermittent compression device requiring a minimum volume of air per pulsation.
Another object is to provide a blood circulation aid which will fit a wide variety of patients without requiring any modification or adjustments.
Another object of the present invention is to provide a disposable device of simple construction which is of a universal shape in that it can be applied to either the left or the right foot with the same effect.
Another object is to provide a device of great simplicity and ease-of-use in contrast to other devices designed for the purpose of aiding blood flow in the feet and legs. Related objects include providing a lightweight, simple article that can be easily and quickly applied to the foot while still achieving the other objects of the invention.
Another object of the invention is to provide a blood flow improvement device which, due to its inherent low manufacturing cost, is practical to use as a disposable item rather than cleaning and reusing.
Still another object is to provide a cyclic compression device which achieves optimum compression and optimum blood flow enhancement in a manner that minimizes anxiety and discomfort to the patient.
Other objects relate to the convenience of the product. It is desired to provide a complete system that can be hand carried to the patient and easily and securely deployed without concern about compatibility with the bed on which the product is to be deployed. A compact, easily-stored and minimally-obtrusive product is also sought.
The present invention addresses the foregoing and many other objects by providing an ingenious article that integrates a compression bladder and its entire mounting, stabilizing and adjustment systems into a simple and economical construction coupled with a control system and housing that greatly surpass prior devices both in utility and ingenuity.
The present invention will typically comprise a foot wrap device made from two sheets of fabric sewn or welded together to form an inflatable pocket or bladder that preferably constitutes as much of the device as possible without creating a bladder that is too uncomfortable or too large to be adequately inflated. One aspect of the invention relates to the roughly T-shaped or L-shaped configuration of its foot wrap, with at least one portion or segment wrapping around the bottom of the foot and a second portion or segment wrapping around the back of the heel and ankle regions of the lower leg. As will be described with reference to the preferred embodiments, the invention may include various extensions or tabs provided to operatively join with other extensions, tabs or the like, as may be beneficial for comfort and efficacy. In the preferred embodiments, both inner and outer fabric layers are cut from the same pattern.
Fasteners formed integral with the extensions enable releasable application on the foot. Preferably, such fasteners include Velcro hook connectors, and the outer surface of the foot wrap is formed of Velcro loop material (or the equivalent) for mating with the hook connectors. The inner layer of the foot wrap is preferably a vapor permeable material having greater elasticity than the outer layer. Both fabrics are preferably impermeable to air and capable of being fused together by heat welding or the like. A filling tube may be sealed into the inflatable bladder or pocket through the outer fabric layer.
In the first embodiment, the complete foot wrap weighs only a few ounces and is soft and pliable. When it is properly applied, a first dimpled or segmented portion of the inflatable bladder wraps around the main part of the foot and fastens to itself. Another portion is joined integrally in fluid communication with the first but wraps around behind the heel and ankle regions of the lower leg. The second portion fastens to the outside surface of either itself or the other portion. Thus, the foot is almost completely enclosed and surrounded by the inflatable bladder, and the device securely holds itself in place on the foot in order to compress as much of the foot as feasible when the bladder is inflated.
Fluid for such inflation may be supplied by one of the pump systems well known in the art, although the preferred embodiment includes and provides several advancements over that art. The preferred embodiment includes a pump that operates in a pulsed sequence that can be adjusted for any desired frequency and intensity according to the prescribed treatment. Preferably the pump/control is set to compress the foot to pressures in the range between 120 and 190 mm Hg and to hold it in that pressure range for two seconds every fifteen seconds. This pressure range is generally accepted by Applicant to ensure closure of the veins in the foot, although lower pressures may be partially effective as well.
The preferred embodiments uniquely integrate more fundamental aspects of the invention together with cushioning means for minimizing localized pressure concentrations acting on the foot, thereby inhibiting skin breakdown on the foot, especially its most vulnerable areas. Optimum compression of the foot is ensured by enclosing as much of the squeezable portion of the foot as is feasible. In the first embodiment, the inner and outer sheets are joined together at circular portions in the interior of its inflatable bladder to help prevent excessive inflation, particularly over regions of the foot that are less compressible. This further optimizes compression of the foot to ensure optimum blood flow enhancement. Holes may be provided through the wrap at those circular portions to further enhance breathability of the patient""s skin.
The present invention also includes a unique pressure source for supplying pressure to the referenced foot wraps. Pressure feedback control of the pressure supplied by the pressure source is provided even during the then-current compression cycle. The feedback system overcomes some of the difficulties inherent in its objects by incorporating spike eliminators, as well as error detection means for alarming the operator of error conditions such as kinked hoses or disconnected foot wraps. The spike eliminator may include an accumulator, possibly in combination with a flow restrictor. The accumulator and restrictor are configured in a way that helps prevent the pressure sensors from over-responding to initial surges of line pressure. Such surges are otherwise common close to the pressure source with compression devices that provide quick inflation.
More particularly, the pressure sensing and control system may include a transducer, an analog-to-digital converter, and a digital micro-controller that controls a plurality of solenoid valves to adjust the supplied pressure in accordance with operator settings. The micro-controller is interfaced through an operator console having a liquid crystal display and programmable keys to enter operator settings, which are then stored using various memory devices including electronically erasable programmable read only memory.
The combination of all the foregoing in an operative system is thought to be very beneficial, especially packaged in a housing that can be releasably mounted on the foot board of a standard hospital bed by means of a pair of opposite, retractable mounting hooks having sloped surfaces for biasing the source toward said foot board and having knobs at the distal ends thereof for helping retain the hooks on the foot board.
Numerous other features, advantages, and objects of the invention are set forth and will be evident from the following more detailed descriptions of certain preferred embodiments, particularly when considered in light of the prior art together with the accompanying drawings and appended claims.